From f0504fa6d2e9f09783b51d85073017c1260d26af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Damian=20B=C3=BCchel?= <damian.buechel@let.ethz.ch>
Date: Fri, 13 Mar 2020 15:56:32 +0100
Subject: [PATCH] SEBWIN-362: Implemented basic load error page for browser.

---
 .../BrowserApplicationInstance.cs             |  4 +-
 SafeExamBrowser.Browser/BrowserControl.cs     | 18 +++++
 .../Handlers/ResourceHandler.cs               | 36 +++------
 .../{Filters => Pages}/BlockedContent.html    |  0
 .../{Filters => Pages}/BlockedPage.html       |  0
 SafeExamBrowser.Browser/Pages/HtmlLoader.cs   | 75 +++++++++++++++++++
 SafeExamBrowser.Browser/Pages/LoadError.html  | 14 ++++
 .../SafeExamBrowser.Browser.csproj            |  8 +-
 SafeExamBrowser.I18n.Contracts/TextKey.cs     |  2 +
 SafeExamBrowser.I18n/Data/de.xml              |  8 +-
 SafeExamBrowser.I18n/Data/en.xml              |  6 ++
 11 files changed, 141 insertions(+), 30 deletions(-)
 rename SafeExamBrowser.Browser/{Filters => Pages}/BlockedContent.html (100%)
 rename SafeExamBrowser.Browser/{Filters => Pages}/BlockedPage.html (100%)
 create mode 100644 SafeExamBrowser.Browser/Pages/HtmlLoader.cs
 create mode 100644 SafeExamBrowser.Browser/Pages/LoadError.html

diff --git a/SafeExamBrowser.Browser/BrowserApplicationInstance.cs b/SafeExamBrowser.Browser/BrowserApplicationInstance.cs
index 60065a7c..292577f8 100644
--- a/SafeExamBrowser.Browser/BrowserApplicationInstance.cs
+++ b/SafeExamBrowser.Browser/BrowserApplicationInstance.cs
@@ -17,6 +17,7 @@ using SafeExamBrowser.Browser.Contracts.Filters;
 using SafeExamBrowser.Browser.Events;
 using SafeExamBrowser.Browser.Filters;
 using SafeExamBrowser.Browser.Handlers;
+using SafeExamBrowser.Browser.Pages;
 using SafeExamBrowser.Configuration.Contracts;
 using SafeExamBrowser.I18n.Contracts;
 using SafeExamBrowser.Logging.Contracts;
@@ -115,6 +116,7 @@ namespace SafeExamBrowser.Browser
 			var displayHandler = new DisplayHandler();
 			var downloadLogger = logger.CloneFor($"{nameof(DownloadHandler)} #{Id}");
 			var downloadHandler = new DownloadHandler(appConfig, settings, downloadLogger);
+			var htmlLoader = new HtmlLoader(text);
 			var keyboardHandler = new KeyboardHandler();
 			var lifeSpanHandler = new LifeSpanHandler();
 			var requestFilter = new RequestFilter();
@@ -138,7 +140,7 @@ namespace SafeExamBrowser.Browser
 
 			InitializeRequestFilter(requestFilter);
 
-			control = new BrowserControl(contextMenuHandler, dialogHandler, displayHandler, downloadHandler, keyboardHandler, lifeSpanHandler, requestHandler, startUrl);
+			control = new BrowserControl(contextMenuHandler, dialogHandler, displayHandler, downloadHandler, htmlLoader, keyboardHandler, lifeSpanHandler, requestHandler, startUrl);
 			control.AddressChanged += Control_AddressChanged;
 			control.LoadingStateChanged += Control_LoadingStateChanged;
 			control.TitleChanged += Control_TitleChanged;
diff --git a/SafeExamBrowser.Browser/BrowserControl.cs b/SafeExamBrowser.Browser/BrowserControl.cs
index 4a70e324..ce340caf 100644
--- a/SafeExamBrowser.Browser/BrowserControl.cs
+++ b/SafeExamBrowser.Browser/BrowserControl.cs
@@ -8,6 +8,7 @@
 
 using CefSharp;
 using CefSharp.WinForms;
+using SafeExamBrowser.Browser.Pages;
 using SafeExamBrowser.UserInterface.Contracts.Browser;
 using SafeExamBrowser.UserInterface.Contracts.Browser.Events;
 
@@ -19,6 +20,8 @@ namespace SafeExamBrowser.Browser
 		private IDialogHandler dialogHandler;
 		private IDisplayHandler displayHandler;
 		private IDownloadHandler downloadHandler;
+		private string errorPage;
+		private HtmlLoader htmlLoader;
 		private IKeyboardHandler keyboardHandler;
 		private ILifeSpanHandler lifeSpanHandler;
 		private IRequestHandler requestHandler;
@@ -53,6 +56,7 @@ namespace SafeExamBrowser.Browser
 			IDialogHandler dialogHandler,
 			IDisplayHandler displayHandler,
 			IDownloadHandler downloadHandler,
+			HtmlLoader htmlLoader,
 			IKeyboardHandler keyboardHandler,
 			ILifeSpanHandler lifeSpanHandler,
 			IRequestHandler requestHandler,
@@ -62,6 +66,7 @@ namespace SafeExamBrowser.Browser
 			this.dialogHandler = dialogHandler;
 			this.displayHandler = displayHandler;
 			this.downloadHandler = downloadHandler;
+			this.htmlLoader = htmlLoader;
 			this.keyboardHandler = keyboardHandler;
 			this.lifeSpanHandler = lifeSpanHandler;
 			this.requestHandler = requestHandler;
@@ -70,6 +75,7 @@ namespace SafeExamBrowser.Browser
 		public void Initialize()
 		{
 			AddressChanged += (o, args) => addressChanged?.Invoke(args.Address);
+			LoadError += BrowserControl_LoadError;
 			LoadingStateChanged += (o, args) => loadingStateChanged?.Invoke(args.IsLoading);
 			TitleChanged += (o, args) => titleChanged?.Invoke(args.Title);
 
@@ -80,6 +86,8 @@ namespace SafeExamBrowser.Browser
 			LifeSpanHandler = lifeSpanHandler;
 			MenuHandler = contextMenuHandler;
 			RequestHandler = requestHandler;
+
+			errorPage = htmlLoader.LoadErrorPage();
 		}
 
 		public void NavigateBackwards()
@@ -111,5 +119,15 @@ namespace SafeExamBrowser.Browser
 		{
 			GetBrowser().SetZoomLevel(level);
 		}
+
+		private void BrowserControl_LoadError(object sender, LoadErrorEventArgs e)
+		{
+			var html = string.Copy(errorPage);
+
+			html = html.Replace("%%STATUS%%", $"{e.ErrorText} ({e.ErrorCode})");
+			html = html.Replace("%%URL%%", e.FailedUrl);
+
+			e.Frame.LoadHtml(html, true);
+		}
 	}
 }
diff --git a/SafeExamBrowser.Browser/Handlers/ResourceHandler.cs b/SafeExamBrowser.Browser/Handlers/ResourceHandler.cs
index 4d547c65..7cdf0fec 100644
--- a/SafeExamBrowser.Browser/Handlers/ResourceHandler.cs
+++ b/SafeExamBrowser.Browser/Handlers/ResourceHandler.cs
@@ -8,14 +8,12 @@
 
 using System;
 using System.Collections.Specialized;
-using System.IO;
 using System.Net.Mime;
-using System.Reflection;
 using System.Security.Cryptography;
 using System.Text;
 using CefSharp;
 using SafeExamBrowser.Browser.Contracts.Filters;
-using SafeExamBrowser.Browser.Filters;
+using SafeExamBrowser.Browser.Pages;
 using SafeExamBrowser.Configuration.Contracts;
 using SafeExamBrowser.I18n.Contracts;
 using SafeExamBrowser.Logging.Contracts;
@@ -32,6 +30,7 @@ namespace SafeExamBrowser.Browser.Handlers
 		private string browserExamKey;
 		private IResourceHandler contentHandler;
 		private IRequestFilter filter;
+		private HtmlLoader htmlLoader;
 		private ILogger logger;
 		private IResourceHandler pageHandler;
 		private BrowserSettings settings;
@@ -42,6 +41,7 @@ namespace SafeExamBrowser.Browser.Handlers
 			this.appConfig = appConfig;
 			this.algorithm = new SHA256Managed();
 			this.filter = filter;
+			this.htmlLoader = new HtmlLoader(text);
 			this.logger = logger;
 			this.settings = settings;
 			this.text = text;
@@ -186,9 +186,14 @@ namespace SafeExamBrowser.Browser.Handlers
 
 		private IResourceHandler ResourceHandlerFor(ResourceType resourceType)
 		{
-			if (contentHandler == default(IResourceHandler) || pageHandler == default(IResourceHandler))
+			if (contentHandler == default(IResourceHandler))
 			{
-				InitializeResourceHandlers();
+				contentHandler = CefSharp.ResourceHandler.FromString(htmlLoader.LoadBlockedContent());
+			}
+
+			if (pageHandler == default(IResourceHandler))
+			{
+				pageHandler = CefSharp.ResourceHandler.FromString(htmlLoader.LoadBlockedPage());
 			}
 
 			switch (resourceType)
@@ -200,26 +205,5 @@ namespace SafeExamBrowser.Browser.Handlers
 					return contentHandler;
 			}
 		}
-
-		private void InitializeResourceHandlers()
-		{
-			var assembly = Assembly.GetAssembly(typeof(RequestFilter));
-			var contentMessage = text.Get(TextKey.Browser_BlockedContentMessage);
-			var contentStream = assembly.GetManifestResourceStream($"{typeof(RequestFilter).Namespace}.BlockedContent.html");
-			var pageButton = text.Get(TextKey.Browser_BlockedPageButton);
-			var pageMessage = text.Get(TextKey.Browser_BlockedPageMessage);
-			var pageTitle = text.Get(TextKey.Browser_BlockedPageTitle);
-			var pageStream = assembly.GetManifestResourceStream($"{typeof(RequestFilter).Namespace}.BlockedPage.html");
-			var contentHtml = new StreamReader(contentStream).ReadToEnd();
-			var pageHtml = new StreamReader(pageStream).ReadToEnd();
-
-			contentHtml = contentHtml.Replace("%%MESSAGE%%", contentMessage);
-			contentHandler = CefSharp.ResourceHandler.FromString(contentHtml);
-
-			pageHtml = pageHtml.Replace("%%MESSAGE%%", pageMessage).Replace("%%TITLE%%", pageTitle).Replace("%%BACK_BUTTON%%", pageButton);
-			pageHandler = CefSharp.ResourceHandler.FromString(pageHtml);
-
-			logger.Debug("Initialized resource handlers for blocked requests.");
-		}
 	}
 }
diff --git a/SafeExamBrowser.Browser/Filters/BlockedContent.html b/SafeExamBrowser.Browser/Pages/BlockedContent.html
similarity index 100%
rename from SafeExamBrowser.Browser/Filters/BlockedContent.html
rename to SafeExamBrowser.Browser/Pages/BlockedContent.html
diff --git a/SafeExamBrowser.Browser/Filters/BlockedPage.html b/SafeExamBrowser.Browser/Pages/BlockedPage.html
similarity index 100%
rename from SafeExamBrowser.Browser/Filters/BlockedPage.html
rename to SafeExamBrowser.Browser/Pages/BlockedPage.html
diff --git a/SafeExamBrowser.Browser/Pages/HtmlLoader.cs b/SafeExamBrowser.Browser/Pages/HtmlLoader.cs
new file mode 100644
index 00000000..569ab635
--- /dev/null
+++ b/SafeExamBrowser.Browser/Pages/HtmlLoader.cs
@@ -0,0 +1,75 @@
+/*
+ * Copyright (c) 2020 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using System.IO;
+using System.Reflection;
+using SafeExamBrowser.I18n.Contracts;
+
+namespace SafeExamBrowser.Browser.Pages
+{
+	internal class HtmlLoader
+	{
+		private IText text;
+
+		internal HtmlLoader(IText text)
+		{
+			this.text = text;
+		}
+
+		internal string LoadBlockedContent()
+		{
+			var assembly = Assembly.GetAssembly(typeof(HtmlLoader));
+			var path = $"{typeof(HtmlLoader).Namespace}.BlockedContent.html";
+
+			using (var stream = assembly.GetManifestResourceStream(path))
+			using (var reader = new StreamReader(stream))
+			{
+				var html = reader.ReadToEnd();
+
+				html = html.Replace("%%MESSAGE%%", text.Get(TextKey.Browser_BlockedContentMessage));
+
+				return html;
+			}
+		}
+
+		internal string LoadBlockedPage()
+		{
+			var assembly = Assembly.GetAssembly(typeof(HtmlLoader));
+			var path = $"{typeof(HtmlLoader).Namespace}.BlockedPage.html";
+
+			using (var stream = assembly.GetManifestResourceStream(path))
+			using (var reader = new StreamReader(stream))
+			{
+				var html = reader.ReadToEnd();
+
+				html = html.Replace("%%BACK_BUTTON%%", text.Get(TextKey.Browser_BlockedPageButton));
+				html = html.Replace("%%MESSAGE%%", text.Get(TextKey.Browser_BlockedPageMessage));
+				html = html.Replace("%%TITLE%%", text.Get(TextKey.Browser_BlockedPageTitle));
+
+				return html;
+			}
+		}
+
+		internal string LoadErrorPage()
+		{
+			var assembly = Assembly.GetAssembly(typeof(HtmlLoader));
+			var path = $"{typeof(HtmlLoader).Namespace}.LoadError.html";
+
+			using (var stream = assembly.GetManifestResourceStream(path))
+			using (var reader = new StreamReader(stream))
+			{
+				var html = reader.ReadToEnd();
+
+				html = html.Replace("%%MESSAGE%%", text.Get(TextKey.Browser_LoadErrorPageMessage));
+				html = html.Replace("%%TITLE%%", text.Get(TextKey.Browser_LoadErrorPageTitle));
+
+				return html;
+			}
+		}
+	}
+}
diff --git a/SafeExamBrowser.Browser/Pages/LoadError.html b/SafeExamBrowser.Browser/Pages/LoadError.html
new file mode 100644
index 00000000..880682bc
--- /dev/null
+++ b/SafeExamBrowser.Browser/Pages/LoadError.html
@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<html style="height: 100%; width: 100%">
+<head>
+    <meta charset="utf-8" />
+    <title>%%TITLE%%</title>
+</head>
+<body style="background-color: lightgray; display: table; font-family: 'Segoe UI'; height: 98%; text-align: center; width: 99%">
+    <div style="display: table-cell; vertical-align: middle">
+        <h1 style="color: red">%%TITLE%%</h1>
+        <p>%%MESSAGE%%</p>
+        <p style="font-weight: bold">%%STATUS%%</p>
+    </div>
+</body>
+</html>
\ No newline at end of file
diff --git a/SafeExamBrowser.Browser/SafeExamBrowser.Browser.csproj b/SafeExamBrowser.Browser/SafeExamBrowser.Browser.csproj
index c12cfa4e..ee4cac5a 100644
--- a/SafeExamBrowser.Browser/SafeExamBrowser.Browser.csproj
+++ b/SafeExamBrowser.Browser/SafeExamBrowser.Browser.csproj
@@ -91,6 +91,7 @@
     <Compile Include="Handlers\LifeSpanHandler.cs" />
     <Compile Include="Handlers\RequestHandler.cs" />
     <Compile Include="Handlers\ResourceHandler.cs" />
+    <Compile Include="Pages\HtmlLoader.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>
@@ -129,8 +130,11 @@
     </None>
   </ItemGroup>
   <ItemGroup>
-    <EmbeddedResource Include="Filters\BlockedContent.html" />
-    <EmbeddedResource Include="Filters\BlockedPage.html" />
+    <EmbeddedResource Include="Pages\BlockedContent.html" />
+    <EmbeddedResource Include="Pages\BlockedPage.html" />
+  </ItemGroup>
+  <ItemGroup>
+    <EmbeddedResource Include="Pages\LoadError.html" />
   </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <PropertyGroup>
diff --git a/SafeExamBrowser.I18n.Contracts/TextKey.cs b/SafeExamBrowser.I18n.Contracts/TextKey.cs
index 2e41005c..d356628f 100644
--- a/SafeExamBrowser.I18n.Contracts/TextKey.cs
+++ b/SafeExamBrowser.I18n.Contracts/TextKey.cs
@@ -20,6 +20,8 @@ namespace SafeExamBrowser.I18n.Contracts
 		Browser_BlockedPageButton,
 		Browser_BlockedPageMessage,
 		Browser_BlockedPageTitle,
+		Browser_LoadErrorPageMessage,
+		Browser_LoadErrorPageTitle,
 		Browser_Name,
 		Browser_Tooltip,
 		BrowserWindow_DeveloperConsoleMenuItem,
diff --git a/SafeExamBrowser.I18n/Data/de.xml b/SafeExamBrowser.I18n/Data/de.xml
index 7c02d2bd..ac5affbc 100644
--- a/SafeExamBrowser.I18n/Data/de.xml
+++ b/SafeExamBrowser.I18n/Data/de.xml
@@ -18,6 +18,12 @@
     <Entry key="Browser_BlockedPageTitle">
         Seite blockiert
     </Entry>
+    <Entry key="Browser_LoadErrorPageMessage">
+        Beim Laden der Seite "%%URL%%" ist folgender Fehler aufgetreten:
+    </Entry>
+    <Entry key="Browser_LoadErrorPageTitle">
+        Seiten-Ladefehler
+    </Entry>
     <Entry key="Browser_Name">
         Browser
     </Entry>
@@ -139,7 +145,7 @@
         Automatisches Beenden fehlgeschlagen
     </Entry>
     <Entry key="MessageBox_BrowserNavigationBlocked">
-        Zugriff auf "%%URL%%" is gemäss der aktiven Konfiguration nicht erlaubt.
+        Zugriff auf "%%URL%%" ist gemäss der aktiven Konfiguration nicht erlaubt.
     </Entry>
     <Entry key="MessageBox_BrowserNavigationBlockedTitle">
         Seite blockiert
diff --git a/SafeExamBrowser.I18n/Data/en.xml b/SafeExamBrowser.I18n/Data/en.xml
index ab3c2d1b..82e3149b 100644
--- a/SafeExamBrowser.I18n/Data/en.xml
+++ b/SafeExamBrowser.I18n/Data/en.xml
@@ -18,6 +18,12 @@
     <Entry key="Browser_BlockedPageTitle">
         Page Blocked
     </Entry>
+    <Entry key="Browser_LoadErrorPageMessage">
+        An error occurred while loading page "%%URL%%":
+    </Entry>
+    <Entry key="Browser_LoadErrorPageTitle">
+        Page Load Error
+    </Entry>
     <Entry key="Browser_Name">
         Browser
     </Entry>